r 54 
Notes on Recent Literature. 
FOSSIL PLANTS. 
M. PAUL BERTRAND ON THE STEMS BELONGING 
TO CLEPSYDROPSIS. 
Last November M. Paul Bertrand published a short report in 
the “ Comptes Rendus de l’Academie des Sciences ” on the steins 
belonging to Clepsydropsis, a genus of Unger’s revived for certain 
petioles hitherto supposed to be distinctly Botryopteridean. The 
best known species of Clepsydropsis is probably that described as 
Rachiopteris duplex by Williamson. The vascular bundle of this 
petiole is shaped like an hour-glass; the species is sometimes 
included in the genus Zygopteris, the two swollen ends of the hour¬ 
glass representing thickened side-pieces of the H-shaped trace of 
that genus. It is, therefore, very interesting that M. Paul Bertrand, 
from a careful comparison of the petiolar bundles of Clepsydropsis 
with the structure of the stem at the departure of the trace in 
Cladoxylon and in Medullosa ( Steloxylon ) Ludivigi, should have 
come to the conclusion that the first-mentioned genus represents the 
petioles of the two latter forms. In the case of Medullosa 
(Steloxylon) Ludivigi such a view is supported by the association 
of this type of stem with Clepsydropsis Kirgisica. 
These fossils from the Lower Culm are of great antiquity, and 
without necessarily accepting M. Paul Bertrand’s view that 
Clepsydropsis appears to be very primitive, and “ infinitely closer 
than any other plant as yet described ” to a form in which 
Lycopods, Ferns and Medulloseae ultimately converge, it is obvious 
that the discovery that Botryopteridean petioles were associated 
with stems included in the Cycadofilices on account of their 
anatomy is very remarkable. The significance of this circumstance 
is enhanced by the similarity (recognized as early as 1881 by 
Dawson) between Cladoxylon and Asterochlaena (his Asteropteris ), 
and by the fact that Botrychioxylon, regarded as one of the 
Botryopterideae, possessed a considerable amount of secondary 
xylem. 1 
A certain number of Cycadofilicinean stems are now known to 
have belonged to seed-bearing plants and suspicion has fallen on 
many others. As other Medulloseae were certainly Pteridosperms, 
some doubt is naturally cast upon the cryptogamic nature of 
Medullosa ( Steloxylon) Ludivigi, although this species is not a true 
or typical Medullosa. But as its petioles and those of Cladoxylon 
appear to belong to the same “genus” ( Clepsydropsis ), Cladoxylon 
itself may turn out to be a Pteridosperm, although further and more 
direct evidence would be wanted to confirm the suspicion. Further 
the reference of Clepsydropsis to Cycadofilicinean stems throws 
some doubt on the cryptogamic nature of the Botryopterideae, now 
frequently regarded as the most important Palaeozoic group of 
“ Ferns”. 1 This doubt must rest at least on the Zygoptereae (to 
1 D. H. Scott. “ Studies in Fossil Botany.” Second Edition, 
Vol. I., 1908. 
